Melatonin Used to Restore Sleep Patterns in Blind People

Editor's Note: Editor's Note: The following is reprinted from The New York Times, Late Edition (East Coast), June 22, 1999.

In the early 1970's, Dr. James Stevenson, then a graduate student in psychology at Stanford University, developed a theory about why he had so much trouble sleeping. Dr. Stevenson, who had been blind from birth, suffered insomnia at night, and in the daytime experienced "sleep attacks," which arrived one hour later each day, playing havoc with his efforts to get to classes on time. He had read that in blinded animals, the body's clock, normally harnessed to the 24-hour cycle of daylight and darkness, often goes into free run, shifting sleep patterns. His own sleeping difficulties, Dr. Stevenson suspected, might have a similar origin.

A sleep researcher, Dr. Laughton Miles, later confirmed what Dr. Stevenson had concluded: In the absence of light, his body had taken up a free-running, 24.9-hour circadian rhythm of sleep and wakefulness, a schedule that shifted his natural sleeping time back by nearly an hour each day.

But Dr. Miles, who in 1977 published a scientific report on Dr. Stevenson's case, could find no way to fix the problem, nor could other researchers, who have spent two decades seeking effective treatments for the sleep problems caused by free-running circadian rhythms, which affect about half the 200,000 Americans who are totally blind. If a study to be presented today at the annual meeting of the Associated Profession Sleep Societies in Orlando, FLA., holds up, however, the search may finally be over.

Dr. Robert L. Sack, Dr. Alfred J. Lewy and Richard L. Brandes of the Sleep and Mood Disorders Laboratory at Oregon Health Sciences University, are scheduled to present their finding that a daily 10-milligram dose of the hormone melatonin successfully "entrained" the free- running rhythms of six out of seven totally blind subjects, returning them to a normal, 24-hour sleep pattern.

"Even entraining one blind person with melatonin is important," said Dr. Charmane Eastman, director of the Biological Rhythms Research Laboratory at Rush Presbyterian-St. Lukes Medical Centre in Chicago. The new study, she said, has implications not only for the blind, who often list sleep problems as one of the most difficult aspects of their disability, but also for sighted people, whose circadian rhythms can be altered by jet lag or shift work.

Dr. Lewy, director of the sleep lab at Oregon, said, "Totally blind people offer a natural way to study the human body clock, without the interference of light cues." In an earlier study, the researchers tried using a 5-milligram dose of melatonin without success. "We got some shifting of rhythms, but we weren't able to establish a clear 24-hour cycle," Dr. Sack said.

A few other investigators have reported single cases in which melatonin corrected free-running sleep-wake cycles in blind people. And Dr. Stevenson, now a research psychologist at NASA Ames Research Centre in Mountainview, Calif., said he began taking melatonin before bedtime in 1987, and now sleeps normally. But the new study compared melatonin with placebo pills in a group of subjects.

Melatonin is secreted by the pineal gland-a tiny structure deep in the brain-and helps regulate the body's biological clock. In sighted people, melatonin secretion is synchronised with the 24-hour cycle of daylight and darkness, turning on at nightfall, and continuing for about 12 hours. But in the absence of light, most people's body clocks run on a cycle slightly longer than 24 hours, Dr. Sack said.

The hormone is also sold over the counter as a nutritional supplement, usually in 3-milligram tablets. Taken in the afternoon, it shifts the body's clock earlier, tricking it into thinking dusk has already fallen. Taken in the morning, however, it delays the clock, as if dawn had not yet arrived.

Scientists still know little about the effects of melatonin at different dosages: In sleep studies, researchers have used doses as small as .3 milligrams and as large as 75 milligrams or higher. Dr. Sack said for some blind people 10 milligrams may be more than is needed. He and his colleagues are conducting further research to see if dosages between 5 and 10 milligrams are equally effective.

In the study, the subjects, who did not know which treatment they were receiving, took melatonin an hour before bedtime for a period of weeks, then were switched to a dummy pill, or vice versa. The length of time it took for the melatonin to shift rhythms back to normal varied from person to person. "Without knowledge of a person's circadian phase," Dr. Sack and his colleagues wrote, "it may be difficult to know the best day for initiating melatonin treatment; thus entrainment may not occur for weeks or months."

Clifton Zang, a 47-year-old man from Portland who has been totally blind since being hit in the head by a stray bullet while sitting in his pickup truck 16 years ago, said the benefits of melatonin became apparent not long after he started taking the supplement. "Before the study, I had no control of my sleep," Mr. Zang said. "I'd sleep any time of the day or night. I'd be awake at 2 in the morning and fall asleep at noon. But since I've been on the melatonin I go to sleep at 11 o'clock and wake up at 5, 6 or 7."